Defoliating cotton with isooctyl xanthoacetic acid



United States Patent DEFOLIATING COTTON WITH ISOOCTYL XANTHOACETIC ACID William H. Brugmann, Jr., Milltown, Harry W. Rudel,

Roselle, and Jeffrey H. Bartlett, Westfield, N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware N Drawing. Application December 9, 1955 Serial No. 551,992

1 Claim. 01. 71- -z.7

This invention relates to improved compositions and methods for defoliating plants. More particularly it relates to improved aqueous emulsions for carrying out these purposes containing as the active ingredient alkoxy xanthogen acetic acid.

The importance and desirability of defoliating living plants is well known. Of particular widespread economic importance is the defoliation of cotton, especially since the successful development of the mechanical cotton picker. This latter development has promoted much research and development in the field of artificial defoliation. Use of defoliants thus increases the efliciency of mechanical cotton pickers. They permit farmers to harvest crops without waiting for frost to naturally defoliate the plant.

It has now been found that particular multi component aqueous emulsions having as the active ingredient alkoxy xanthogen acetic acid are especially effective defoliants. These emulsions comprise in addition to the active ingredients and water, a mineral spray oil and an oil soluble emulsifying agent. All these four components in combination are necessary to secure the desired defoliating effect without deleteriously affecting the remainder of the plant, e.g., the active ingredient without the oil in the formulation has little utility for this purpose. The concentrations, as explained in further detail below, are also extremely important in this connection as, e.g., lesser quantities of the active compound do not produce the desired results.

The active compound of this invention is in general prepared by the reaction of the corresponding alcoholate with carbon disulfide or by the reaction of the anhydrous alcohol with carbon disulfide and alkaline metal hydroxide.

The active compound of this invention may thus be represented by the following formula The isooctyl portion of the molecule is preferably derived from isooctyl alcohols produced by the well known 0x0 process, e.g., see U.S. Patent 2,658,923, issued November 10, 1953.

The mineral oil carriers which may be utilized are, for example, any of the normally used horticultural spray oils. For practical reasons these oils will usually be mineral oils, but oils of animal or vegetable origin or synthetic oils are also satisfactory. In general, the oils should be of a relatively bland, non-toxic nature since any composition which would kill the plant outright could not promote the development of the abscission layers which is necessary to successful defoliation. In order to avoid objectionable staining of the cotton fibers, oils with only a fairly light color should be used.

These oils typically have a boiling point in the range of 250 to 550 F., a viscosity in the range of 30 to 200 SSU/100 F. and the petroleum oils are predominantly at least 50 wt. percent to 75 wt. percent parafiinc or naphthenic. The synthetic oxygenated fraction known as 0x0 Z,93,348 Patented Sept. 8, 1959 ice bottoms can also be utilized, and are intended to be connoted by the term mineral spray oil." The preparation and the character of these Oxo bottoms are described in detail in U.S. Patent 2,586,681. Blends of the mineral spray oil can also be utilized.

The emulsifying agents that can be utilized are oil soluble emulsifying agents known to the art. These include by way of example by trade name and chemical description as follows: Igepal CO-630, alkyl aryl polyoxyethylene glycol ether; Acto, petroleum sulfonate; Nonisol 210, polyethylene glycol oleate; Tween 21, polyoxyalkylene derivative of sorbitan monolaurate; Triton X45, alkylated aryl polyether alcohol; Mulsor 3CW, long chain fatty acid ester containing multiple ether linkages; and a petroleum sulfonate modified with a minor amount of a non-ionic emulsifier. Blends can be utilized.

The compositions of this invention are thus conveniently made up in the forms of emulsion concentrates containing 5 to 50 wt. percent of the active ingredient, 40 to wt. percent of the mineral spray oil, and 1 to 10 wt. percent of the emulsifier. These concentrates can then be diluted in the field with water so that the emulsion concentrate constitutes from 10 to 50 wt. percent of the total aqueous emulsion formulation. As stated previously the concentrations as well as the compounds are important to secure the desired activity.

The aqueous emulsion is applied to the plants at a rate of 5 to 40 gallons per acre, preferably 5 to 20 gallons per acre. The lower figures are employed in airplane spraying and the upper ones for ground spray equipment. The time of application varies with the plant, e.g., it is most effectively applied to cotton plants EXAMPLE l-PREPARATION OF ACTIVE MATERIALS (A) Preparation of sodium isooctyl xanthate A 5 liter 4 necked flask which was equipped with a stirrer, condenser and thermometer was charged with:

2600 g. isooctyl alcohol-20 moles g. metallic sodium-5 moles By gradually heating to 170 C., all of the sodium reacted with the alcohol forming the alcoholate. The mixture was then cooled to 25 C. and 532 g. (7 moles) of CS was added during 10 minutes at 25 to 35 C. A Dry Ice-alcohol mixture Was used for cooling. Stirring was continued for another half hour.

The above reaction mixture was divided into two equal parts for preparation of products B and C.

(B) Preparation o isooctyl xantlzoacetic acid 2.5 moles g.) of sodium methoxide was dissolved in 400 g. of methanol in a 1 liter Erlenmeyer flask and then cooled in a Dry Ice-alcohol mixture. In a similar way 236.3 g. (2.5 moles) of chloroacetic acid was dissolved in 600 g. of methanol in a 2 liter Erlenmeyer and cooled to l0 C. Then the sodium methoxide solution was added to the chloroacetic acid solution at 0 to 10 C. thus producing sodium chloroacetate.

A 5 liter 4-necked flask equipped with a stirrer, condenser and thermometer was charged with one half of the sodium isooctyl Xanthate mixture as produced in (A) and cooled to 0 C. To this was added the sodium chloroacetate solution as prepared above at to C. Then the entire mixture was heated to 70 C. during 1 hour. The resulting mixture after cooling to 50 C. was filtered through Hyfio and the filtrate evaporated on the steam bath with the aid of nitrogen. The residue was added to 6 liters of water and then given 2 extractions with petroleum ether to remove unreacted isooctyl alcohol. The aqueous layer was then acidified with HCl in the presence of cracked ice and diethyl ether. The ether extract was evaporated and the residue was stripped in a short path still to a pot temperature of 75 C. at 0.6 mm. leaving a bottoms product 466 g. of isooctyl xanthoacetic acid.

EXAMPLE 2 5 usually greater defoliation was obtained with compositions of this invention as contrasted to for the control.

The utilization of the compositions of this invention represents extremely large labor savings and lower grow- 10 ing costs.

It is to be understood that this invention is not limited to the specific examples which have been oifered merely as illustrations, and that modifications may be made without departing from the spirit of this invention.

What is claimed is: A method of defoliating cotton plants which comprises applying to said plants at the rate of 5 to gallons per acre an aqueous emulsion comprising an 20 organic concentrate of 5 to wt. percent of isooctyl xanthoacetic acid as the active ingredient, from 40 to 90 wt. percent of a mineral spray oil, from 1 to 10 wt. percent of an oil soluble emulsifying agent, said concentrate constituting from 10 to 50 wt. percent of the 25 total aqueous emulsion.

Formulation Applic. Est. per

Applied As- Rate, cent Active Ingredient, Wt. percent Carrier, Wt. Emulsifier, Wt. Gal/A. Defoliapercent percent tion Isooctyl xanthogen acetic acid, 10% WS-1449, M1150 73%; 25% emuls. 20

Isooctyl xanthogen acetic acid, 5% d0 20 65 Isooctyl ester of isooctyl xanthogen acetic acid, 8% WS-1449, 87%.. 20% emuls. 20 60-70 Nona WS-1449, 87% 25% emuls 40 20 References Cited in the file of this patent UNITED STATES PATENTS 2,070,634 Werntz Feb. 16, 1937 2,535,877 Stewart Dec. 26, 1950 2,562,011 Baumgartner July 24, 1951 2,600,624 Zoppo June 17, 1952 2,600,861 Englund June 17, 1952 

1. A METHOD OF DEFOLIATING COTTON PLANTS WHICH COMPRISES APPLYING TO SAID PLANTS AT THE RATE OF 5 TO 40 GALLONS PER ACRE AN AQUEOUS EMULSION COMPRISING AN ORGANIC CONCENTRATE OF 5 TO 50 WT. PERCENT OF ISOCTYL XANTHOACETIC ACID AS THE ACTIVE INGREDIENT, FROM 40 TO 90 WT. PERCENT OF A MINERAL SPRAY OIL, FROM 1 TO 10 WT. PERCENT OF AN OIL SOLUBLE EMULSIFYING AGENT, SAID CONCENTRATE CONSTITUTING FROM 10 TO 50 WT. PERCENT OF THE TOTAL AQUEOUS EMULSION. 